FOR about 10 minutes at Celtic Park yesterday the ground shook with the sort of distinct tremors which suggested an Ulster earthquake.

In such times teams find out a lot about themselves. Derry learned that they have the mental fitness to cope with shock waves of adversity. Armagh discovered that they lack the legs and the forwards for the 70 minute haul.

Few teams wake up in the Ulster championship and find everything going right for them. So it was for Armagh yesterday. With the wind and the sun on their backs they popped over four points in the opening eight minutes and the omens suggested more than mere accuracy from Ger Houlahan and Diarmuid Marsden, who shared the early scoring duties.

Armagh were bursting with feverish intent all over the place, in tight exchanges they were sending out all sorts of signals about their raw physicality.

Gerard Reid at full back was almost crazed with passion in the opening half, so much so that many people were surprised he made it to half time without being either dismissed or decapitated. Reid seemed determined to test the long discredited theory that Seamus Downey is windy. By way of reply Downey, the Derry full forward, who sustained a suspected broken jaw in the 10th minute played on influentially until the game was beyond Armagh's reach.

At the time that Downey suffered his injury Donegal referee Michael McGrath was riding the game liking a novice in a big time rodeo. We expected at any minute that he would lose his grip entirely and the game would go bucking off into dangerous territory. Perhaps inhibited by the effects of an early sending off at Clones last week, perhaps just incredibly tolerant of naked violence, McGrath let several incidents flare up and die away without taking serious sanction.

Derry had surprised a few people by persisting with the league final experiment of playing Gary Coleman at full back. He is beginning to look the part. He shared the same difficulties as the rest of the full back line early on, but came into his own in the second half when a tactical switch with Kieran McKeeve left him free to play a more conventional game. He cleaned up everything in front of his goal and distributed calmly.

The beauty of Derry's defensive set up is its fluidity. Henry Downey is the only truly fixed point in the set up, everyone else can move about as Derry need to patch and mend.

Of greater concern to Mullins this week will be the difficulty which the Derry attack have in scoring when Joe Brolly gets bottled up. Yesterday the excellent Colm Hanratty welded himself on to Brolly's back for most of the first half. As such, a fine point from Seamus Downey was Derry's only score from play before the break.

That score by Downey in the 28th minute bought Derry parity for the first time in the game. Six minutes later, Tohill hopped over his fourth free to give them the lead. By then however, several other things had fallen into place. Armagh weren't getting as much out of the congested midfield. Ger Houlahan at centre forward was suffocating for lack of space. His counterpart Damien Barton, was making his spiky presence felt at every turn.

Marsden popped a free over on the brink of half time to leave it at five points apiece going into the break, but Derry carried in all the momentum and all the optimism at that point.

As befits a team of their experience, they came out and finished the business in a 12 minute spell at the start of the second half when they scored 1-4 without reply. Gormley had already popped a free over when, seven minutes into the half, Diamond rampaged into Armagh's square and fed Brolly who tucked away the easy chance. Brolly thrives on these little sequences of Derry dominance. He scored a point a minute later and fed McGurk for another point within seconds. By the time Tohill had popped over another free, Armagh were feeling a certain heaviness in their legs. The goal, in particular, had rocked them back.

Even if they never quite attacked with the same conviction after that, Derry kept plugging away relentlessly. Seven points up after 13 minutes, they conceded a silly enough goal when a punted Ger Houlahan kick was fisted first by Martin Toye and then by substitute Justin McNulty, before the ball entered the net. Marsden missed a kickable free soon after and Derry then closed the door, tight by scoring the next three points.

What late moments of hope Armagh enjoyed came when John Rafferty exploited Derry's old Achilles heel and ran straight at them with the ball. The game was by then, all but drained of interest. Ger Houlahan had a late penalty turned over the crossbar by Jonathon Kelly in the Derry goal.